A new nonlinear equation governing asymptotic dynamics of short surface wav
es is derived by using a short-wave perturbative expansion in an appropriat
e reduction of the Euler equations. This reduction corresponds to a Green-N
aghdi-type equation with a cinematic discontinuity in the surface. The phys
ical system under consideration is an ideal fluid (inviscid, incompressible
and without surface tension) in which takes place a steady surface motion.
An ideal surface wind on a lake which produces surface flow is a physical
environment conducive to the above-mentioned phenomenon. The equation obtai
ned admits peakon solutions with amplitude, velocity and width in interrela
tion.